<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>state</title>
</head>
<div id="app"></div>

<body>
    <script crossorigin src="https://unpkg.com/react@16/umd/react.development.js"></script>
    <script crossorigin src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script>
    <script src="../../node_modules/babel-preset-react-app/index.js"></script>
    <script type="text/babel">
        class HelloMessage extends React.Component {
        render() {
          return <div>Hello</div>;
        }
      }

      ReactDOM.render(<h1>Hello, world!</h1>, document.getElementById("root"));
    </script>
</body>

</html>